Chitosan supported palladium nanoparticles (Pd NPs/CS) catalysts were facilely prepared via an in-situ reduction of PdCl2 method and characterized by various techniques. The results showed that the palladium particles were in the range of 4-8 nm and evenly dispersed on chitosan. Furthermore, the resulting Pd NPs/CS catalysts showed high catalytic activity for the hydrolytic dehydrogenation of ammonia borane (NH3BH3, AB) in aqueous solution. As for the catalytic reaction with an activation energy (E-a) of36.25 kJ mol(-1), the orders of palladium and AB concentrations were 0.81 and 0.45, respectively. The maximum turnover frequency was as high as 24.76 mol(H2).mol(pd)(-1).min(-1) at 30 degrees C. In addition, the Pd NPs/CS catalysts still kept satisfied catalytic activity even after eleven runs.